This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The specific aims are A. To develop novel methods using mass spectrometry to qualitatively (and subsequently, semi-quantitatively or quantitatively) determine the presence of multiple neuropeptides derived from a single gene product (e.g. prodynorphin and processed dynorphin A peptides;proenkephalin and processed enkephalin peptides;proopiomelanocortin (POMC) parent peptide and multiple peptides derived from POMC, adrenocorticotropin hormone (ACTH), beta-endorphin, of gamma-melanocyte-stimulating hormone (MSH). B.To use these novel techniques (alone or in combination with HPLC and/or RIA) for the simultaneous qualitative and/or quantitative analysis of opioid peptides and other neuropeptides related to the endogenous opioid system (e.g. Corticotropin releasing factor (CRF), cholecystokinin (CCK), substance P and their processed peptides). C. To use these techniques in studies of the effects of alterations in levels of activity of neurotransmitters on the processing of endogenous opioids (e.g. the effects of altered levels of dopamine on dynorphin processing). D. To use these techniques to study the effects of drugs of abuse and potential treatment agents on opioid peptide processing and degradation (e.g. cocaine, morphine and ethanol effects;methadone, nalmefene and fluoxetine effects). We have recently developied a novel multi-stage MS tool for determining specific endogenous extracellular neuropeptides (including vasopressin and oxytocin) in rat